Sawing and other like cutting machines for operating on moving bar or other stock

ABSTRACT

A flying saw machine having a control means for causing a main fluid pressure operated piston and cylinder device to advance substantially in unison with a carriage clamped to and having a cutting tool to cut through the advancing bar stock and be withdrawn therefrom whereupon the clamps release the carriage from the bar stock and said device returns the carriage and cutting tool to a starting position.

United States Patent 2 I {72] Inventors John G. Postins [56] ReferencesCited Wednesbury: UNITED STATES PATENTS v i f-g i lub'lee 1,648,829 11/1927 Sessions 83/294 51 A l N a :23? 2.163.967 6/l939 Strawn etal..83/292 5 ii N 1968 2,287,833 6/1942 Ridgway.... 83/292 e d ir- 2.757.7348/1956 Richardson 83/292 :73} A2325; h/fid l ad lndusu-ies Limited3,081,657 3/I963 Harris 83/294 v smfiordnngland 3,267,783 8/1966 Kepes83/292X a British company Primary ExaminerFrank T. Yost AtmmeyA. YatesDowell [54] SAWING AND OTHER LIKE CUTTING MACHINES FOR OPERATING ONMOVING BAR OR OTHER 7 5 D 2 ABSTRACT: A flying saw machine having acontrol means for aims rawmg causing a main fluid pressure operatedpiston and cylinder .[52] U.S.Cl 83/292, device to advance substantialiyin unison with a carriage 83/294 clamped to and having a cutting tool tocut through the ad- [5 I 1 Int. Cl 823d 25/ I6 vancing bar stock and bewithdrawn therefrom whereupon the [50] Field of Search 83/290. clampsrelease the carriage from the bar stock and said device returns thecarriage and cutting tool to a starting position.

PATENTEUFEBZ' Ian i 5 3.559.520

A TTOR/VE Y5 SAWING AND OTHER LIKE CUTTING MACHINES FOR OPERATING ONMOVING BAR OR OTHER STOCK SUMMARY OF THE INVENTION According to thepresent invention a flying cutting tool machine is provided for cuttingsubstantially horizontally advancing bar stock and having a carriagewith clamping means by which the carriage is clamped to the bar stock ata starting position and also having a cutting tool movable to cutthrough the advancing bar stock and be withdrawn therefrom whereupon theclamping means release the carriage from the bar stock to enable a mainfluid pressure operated piston and cylinder device, which is notattached rigidly to the carriage and does not influence the advancemovement of the carriage. to return the carriage to the startingposition wherein is the improvement that a control means is associatedwith the carriage and with a movable member of the main fluid pressuredevice to cause said movable member of the main fluid pressure device tobe advanced by fluid pressure therein substantially in unison with thecarriage whilst the clamps secure the said carriage to the stock so asto be advanced solely by the stock until the cutting tool has finished acutting operation and is clear of the bar stock and then to cause saidmovable member of the said main fluid pressure device substantiallysimultaneously to return the carriage to the starting position.

BRIEF DESCRIPTION OF THE DRAWINGS A flying saw machine constructed inaccordance with the present invention will now be more particularlydescribed by way of example with reference to the accompanying drawingsDESCRIPTION OF THE PREFERRED EMBODIMENT The flying saw machine comprisesa stationary frame including two horizontal rails 10, 12 disposed one ateach side of the machine and extending in a direction from an intake end14 to a discharge end 16 and on the rails is supported a carriage I8which is thus capable of being advanced and returned in a horizontalplane and in directions from end-to-end of the machine and thearrangement is such that the carriage is advanced by being clamped to acontinuously advancing circular tubular bar or stock 20, advancing inthe direction of the arrow 22, to be cut into predetermined lengths orcutoff portions, and is returned to a starting position shown in FIGS. Iand 2 by a main fluid pressure operating piston and cylinder device 24of which the cylinder 26 is'mounted on brackets 28 clamped to ahorizontal support rail 30.

A removable cover is indicated in dotted lines at 29.

The carriage 18 has pivotally mounted thereto at 31 about a horizontalaxis extending from end-to-end and thus longitudinally of the machine,an arm 32 at the outer end of which is carried a cutting tool in theform of a rotatable saw 34 which rotates about a horizontal axisdisposed longitudinally of the machine and the saw is disposed ingeneral below the path along which the stock is advanced and is fedupwardly to effect a cutting action by means of a feed fluid pressureoperated piston and cylinder device 36 connected to the free end of thearm and to the carriage. The saw is driven by an electric motor 37 alsomounted on the arm 32.

The saw 34 is. in main, enclosed within a box formation 38 of thecarriage and the box formation is provided with a'substantially uprightslot 40 in which a bearing sleeve 42 of the arm moves. In the lowermostposition of the saw, as shown in FIG. 3. the upper edge thereof isdisposed slightly below a lower clamp comprising two barlike jaws 44, 46see FIG. 4, secured to the carriage I8 and said jaws are disposedtransversely of the machine and are spaced apart on opposite sides ofthe saw 34 so that the lower clamp is divided and affords a slot or gap48 between which the saw can be fed upwardly and returned downwardly andthe two jaws are positioned as close' ly as possible to the sides of thesaw so as to be just clear of the saw. The upper faces of the jaws 44,46 are horizontally disposed and are formed of strip rubber or likematerial supported on metal backing bars 50.

Cooperating with the lower divided clamp 44, 46 is an upper dividedclamp which is of inverted V-formation in end elevation as shown in FIG.3 so as to locate the circular bar stock 20 when the stock is grippedbetween the upper and lower clamps and said upper clamp comprises twojaws 52, 54 which are spaced apart to lie on opposite sides of the sawand as closely as possible to the saw so as to be just clear of the sawand so that the gap between the jaws can receive the saw at the end ofthe cutting operation as shown in FIG. 4. The upper clamp may be made ofmetal, fibre or other suitable material and if desired the lower facesof the jaws may be faced with rubber or like material. The jaws may beof various shapes in end elevation so as to be complementary to theprofile of the stock being cut.

The upper and lower clamps thus provide two cooperative pairs of jaws,one pair of jaws 44, 52 being on the advancing stock side of the saw togrip the leading end of the stock and the other pair of jaws 46, 54being on the cutoff portion side of the saw and each pair of cooperativejaws are coplanar in a vertical plane so that the leading end of thestock is clamped to the carriage by the pair of a jaws 44. 52 and alsothe trailing end of the cutoff portion is clamped to the carriage by thepair of jaws 46, 54 during the entire cutting action so that said cutoffportion is advanced by the carriage during the entire cutting action andnot by the saw and the saw does not score the trailing end of the cutoffportion unduly as occurs in previous machines in which the cutoffportion is advanced by the saw and furthermore at the instant at whichthe complete severance is effected between the stock and the cutoffportion both said stock and cutoff portion are clamped securely inposition so that the final cutting action is clean and avoids theformation of pips or flash on the leading and ta trailing ends of thestock and cutoff portion respectively.

The upper clamp 52, 54 is carried at the lower end of a piston rod of aclamp fluid pressure operated piston and cylinder device 56 of which thecylinder is vertically disposed and is carried by a horizontal uppercrossbar 58 at a position between the ends of the crossbar which isdisposed transversely of the machine and forms a part of a pillarstructure of the carriage.

The pillar structure also comprises two vertical pillars 60 disposed atopposite sides of the carriage as shown in FIG. 3 and the upper crossbar58 connects together the upper ends of the pillars of which the lowerends are connected together by a lower horizontal crossbar 62 disposedbelow a backing bar 50. The pillars 60 are slidably supported in bushes59 forming parts of the carriage and screw clamping means are carried bythe bushes and are operable by manually rotatable knobs 61 to clamp thepillar structure to the carriage. The clamps can be released to enablethe pillar structure to be adjusted vertically, to afford a coarseadjustment of the upper clamp to accommodate stock of different sizesafter which the screw clamping means are tightened. The actual verticalclamping movement effected by the upper clamp is performed by theclamping fluid, preferably air, operated device 56 and extends over asmall or fine range of movement such as, for example, approximately 1inch.

Secured to the carriage I8 is a table 63 which is disposed on the cutoffportion side of the saw 34 and said table comprises two bars 65, 67 ofangle section which are-supported at one Above the table there Issupported In a stationary manner an electrical length control switch 79which includes a depending pivoted finger 81 which lies m the path ofadvance of the leading end of a portion of the bar stock being cut andsaid leading end is spaced above the table so as not to be supportedthereby. said portion being supported whilst being cut by the jaws 46.S4. The switch 79 is suitably connected by connections in a circuit (notshown) The main fluid. preferably air. operated piston and cylinderdevice 24 comprises the cylinder 26 which is disposed longitudinally ofthe machine at one side thereof and a piston rod member 64 of the deviceextends from the cylinder towards that end of the machine at which thestock enters the machine and at the end of the piston rod there issecured an operating button 66 having a cylindrical shank 68 formed atthat end adjacent the cylinder with an annular shoulder 70 and the shankis slidably housed in a cylindrical bush 72 secured to the carriage l8and the annular shoulder can abut one end of the bush to return thecarriage to a starting position after the carriage has been advanced asa result of being clamped to the advancing stock in a manner aspreviously described. The end of the operating button includes anadjustable set screw 74 which cooperates with an actuating lever 76 of afollowup fluid pressure release valve 77 carried by the carriage, andwhich actuating lever is pivoted at 78 and is urged by a spring 80 in adirection to resist movement of said lever by the operating button 66.The followup valve is shown diagrammatically as comprising a port 82 atthe end of a pipe 84 and the actuating lever cooperates with the port toopen and close the valve and when the annular shoulder 70 abuts the endof the bush 72 the operating button opens the followup valve which isallowed to close when the operating button is not in contact with theactuating lever and the annular shoulder of the operating button is notin contact with the end of the bush.

The main fluid pressure device 24 is double-acting and the two oppositeends of the cylinder are connected by pipes 86, 88 to a multiway valvewhich is diagrammatically illustrated at 90 and which valve is operatedor controlled by solenoids indicated at 91 in circuit with one or moreelectrical microswitches (not shown) arranged to be automaticallyactuated to obtain a repeating cycle of the machine. The multiway valve90 is connected by a pipe 92 to a main air pressure supply source and isalso connected by the pipe 84 to the followup valve 77 so that the largepressure side of the piston, i.e. not containing the piston rod 64, canbe connected to the followup valve so that the said larger side of thepiston can be opened to exhaust when the actuating lever of the followupvalve is moved into an open position against spring action by theoperating button 66 at the end of the piston rod, and said multiwayvalve is also connected to an adjustable relief valve 93 which can beconnected through said multiway valve to the small pressure side of thepiston, i.e. that side in which the piston rod is disposed.

The cycle of operations of the machine is as follows:

The bar stock is continuously advancing in the direction ofthe arrow 22FIG. 1.

For convenience the cycle is considered to commence at the position inwhich air pressure is on both sides of the piston of the main device 24but the large side of the piston is connected through the pipe 88 to themain supply 92 whereas the small side is connected through the pipe 86to the relief valve 93 and thus to restricted exhaust so that the pistonand thus the carriage 18, on which the clamps 44, 46, 52 and 54 areopened free of the stock 20, are returned to a starting position asshown in FIGS. 1 and 2 against the action of a maintained air pressureon the small side of the piston and which maintained pressure depends onthe setting of the relief valve 93 and prevents the carriage 18 beingshot back to the starting position and this starting position of thecan'iage is held by the main device.

The constantly advancing bar stock then operates the electrical lengthcontrol switch 79 (or alternatively a manually operable start switch canbe actuated) whereby a signal is transmitted to the multiway valve toconnect the small side of the piston of the device 24 to the main airpressure supply 92 and cut off said small side from the relief valve 93and to open the large side of the piston to exhaust through the now openfollowup valve 77 and also to cause the clamps 44. 46. 52 and 54 on thecarriage [8 to secure the carriage to the stock.

As the followup valve 77 is open the piston in the main device 24 rsadvanced by the larger air pressure on said small side of the piston sothat the piston rod 64 and the operating button 66 at the end thereofadvance relatively to the bush 72 on the carriage l8 and thus away fromthe actuating lever 76 of the followup valve 77 to allow the lever to bespring urged into a position closing said valve to stop the exhaust fromthe large side of the piston and thus to stop the advance of the pistonrod. Simultaneously as the clamps have secured the carriage to thestock, the carriage l8 and thus the bush 72 also advance slightly behindthe operating button 66 and as the operating button is stationary thefollowup valve 77 and thus the carriage catch up with the operatingbutton 66 so that the actuating lever 76 of the followup valve 77 ismoved against spring action from a valve-closed position to a valve-openposition. As the followup valve is now open the larger side of thepiston is again open to exhaust the piston is again advanced away fromthe carriage a small distance to allow the followup valve again to closewhereupon the carriage again catches up with the operating button.

Thus the piston of the main device 24 advances in what is apparently astepby-step manner slightly in front of the carriage but in practice thepiston advances fairly steadily and thus said main device advances inunison or substantially in unison with the carriage and never advances asubstantial distance in front of the carriage.

At the commencement of the movement of the carriage 18 by the stock 20from the starting position a further electrical switch (not shown) isoperated to start rotation of the saw 34 but this only occurs forrelatively long cutoff portions of stock and for relatively shortcutofi' portions of stock the saw will be allowed to rotatecontinuously. A further electrical switch (not shown) is also operatedto cause the device 36 to effect a feed movement of the saw upwardly butthis further switch is shunted when relatively short cutoff portions arebeing produced and when the saw is rotating continuouslyand said feedmovement is otherwise obtained.

The saw continues to move upwardly to effect a cutting operation whilstthe carriage continues to advance steadily and whilst the main device 24is either level with or slightly ahead of the carriage.

At the end of the upward feed movement of the saw. the arm 32 carryingthe saw 34 cooperates with an electrical switch 94 carried by the lowercrossbar 62 to actuate a further multiway valve (not shown) and reversethe feed movement of the saw and thus cause the saw to move downwardlybut if an overrun upward movement of the saw occurs, the upwardly movingarm 32 abuts the crossbar whereby a positive safety stopping action isprovided. As previously described during the feed movement of the sawthe stock is cut cleanly without undue score marks and without pips orflash remaining at the ends of the cutoff portions and during thecutting operation the portion of stock being cut off is advanced solelyby the clamps and not by the saw.

in addition to the last mentioned electrical switch 94 two furtherelectrical switches (not shown) are provided and the three switches arearranged in series and of the said two further switches one is manuallyoperable in case of emergency to stop the cutting action and the otherswitch ensures that the saw blade is returned to the bottom positionbefore the carriage reaches the end of its mechanical travel, i.e. themaximum distance of travel of the carriage, which is fixed by the sizeof the machine, so that if by accident the carriage 18 reaches the fulllimit of its travel, the two switches ensure that the saw is returned tothe bottom position and thus under any circumstances the saw, whenwithin the stock. cannot slow down. pause or move m the oppositedirection relative to the stock.

When the saw attains its lowermost position another electrical switch orswitches [not shown) is or are operated to cause the clamps to openwhereby the carriage is freed from the advancing stock and the multiwayvalve 90 is actuated to connect the mains air supply 92 to the largeside of the piston of the main device 24 to return the carriage to thestarting position during which return movement the air from the smallside of the piston is exhausted through the relief valve 93 set at apredetermined pressure and this return movement of the carriage iseffected by the annular shoulder 70 of the operating button abutting theadjacent end of the bush 72. The starting position of the carriage ismaintained by the main fluid pressure operated piston and cylinderdevice 24 until the cycle of operations is automatically recommenccd.

It should be appreciated that the portion of the stock bar being cut issupported above the table 65, 67 solely by the jaws 46. 54 and that thetable only supports the cutoff portion, i.e. after complete severancehas occurred.

The arrangement is such that individual operations of the machine can betested without perfonning the full cycle of operations.

The multiway valve 90, followup valve 77, relief valve 93 and associatedpipe lines. electrical switches and connections thus constitute acontrol means which is associated with and controls the main device 24and the carriage l8 and as a result of the main device remaining at alltimes level with or only slightly in advance of the carriage said deviceonly moves through a distance proportional to the length of the cutoffportions required and does not move through the entire stroke of thedevice unless the length of the cutoff portion requires this and,therefore, the device in the machine according to the present inventiondoes not have to move through a waste" distance during which the stockis advancing and in consequence the machine can cut off shorter portionsof stock than would be possible with known machines of similar sizes.Also, due to the fact that the cutoff portion is advanced by the clampsand not by the saw a more efficient and clean cutting operation isachieved which results in the cutoff portions being accurate in length.

We claim:

I. A flying cutting tool machine for cutting substantially horizontallyadvancing bar stock (20) and having a carriage (18) with clamping means(44, 52, 46, 54) by which the carriage is clamped to the bar stock at astarting position and also having a cutting tool (34) movable to cutthrough the advancing bar stock and be withdrawn therefrom whereupon theclamping means release the carriage from the bar stock to enable a mainfluid pressure operated piston and cylinder device, which is notattached rigidly to the carriage and does not influence the advancemovement of the carriage, to return the carriage to the startingposition wherein is the improvement that a control means (90, 77, 93) isassociated with the carriage (l8) and with a movable member (64) of themain fluid pressure device (24) to cause said movable member (64) of themain fluid pressure device (24) to be advanced by fluid pressure thereinsubstantially in unison with the carriage (18) whilst the clamps securethe said carriage to the stock so as to be advanced solely by the stockuntil the cutting tool (34) has finished a cutting operation and isclear of the bar stock (20) and then to cause said movable member (64)of the said main fluid pressure device (24) substantially simultaneouslyto return the carriage (18) to the starting position.

2. A flying cutting tool machine for cutting substantially horizontallyadvancing bar stock (20) and having a carriage (18) with clamping means(44, 52, 46. 54) by which the carriage is clamped to the bar stock at astarting position and also having a cutting tool (34) movable to cutthrough the advancing bar stock and be withdrawn therefrom whereupon theclamping means release the carriage from the bar stock to enable a mainfluid pressure operated piston and cylinder device, which is notattached rigidly to t not influence the advance movement of thecarriage. it return the carriage to the starting position wherein is theimprovement that a control means comprises a multiway fluid pressurevalve (90) and a followup fluid pressure release valve (77). saidmultiway valve being connected to a fluid pressure supply source (92)and to opposite ends of the main fluid pressure piston and cylinderdevice (24) which is double-acting and said multiway valve being alsoconnected to the followup valve (77) which is supported by and movablewith the carriage (l8) and which followup valve (77) is operablyassociated with the movable member (64) of said main device (24) wherebyduring advance of the carriage (18) by the bar stock from the startingposition the followup valve (77) catches said movable member (64) of themain device (24) to open said followup valve (77) and open one side ofthe said main device (24) to exhaust to permit a greater fluid pressureon the other side of said main device (24) to advance said movablemember (64) of said device away from the followup valve (77) which willthen close to stop further advance of the said movable member (64) ofsaid main device (24) until the carriage (l8) and the followup valve 77)again catch the said movable member (64) of said main device to repeatthe cycle until the tool (34) has finished the cutting operation and isclear of the stock (20) from which the carriage (I8) is then releasedwhereupon the multiway valve (90) connects said one side of the maindevice to the fluid pressure supply (92) and the other side of said maindevice to exhaust to reverse the operation of the said main device (24)and return the carriage 18) to the starting position.

3. A flying cutting tool machine according to claim 2 wherein is theimprovement that said other side of the said main device (24) isconnected to exhaust through a pressure relief valve (93).

4. A flying cutting tool machine according to claim 2 5 wherein is theimprovement that the followup fluid pressure 35- release valve (77)comprises a port (82) connected to the multiway valve (90). an actuatinglever (76), a spring to urge the lever towards the port to close saidvalve, said lever cooperating with an operating button (66) of saidmovable member (64) of the main device (24) whereby the lever is urgedaway from the port to open said valve.

5. A flying cutting tool machine according to claim 4 wherein is theimprovement that the carriage (18) is provided with an abutment (72) andthe operating button (66) is provided with an abutment (70) and saidabutments cooperate to enable the main device (24) to return thecarriage (18) to the starting position and said abutments separate whenthe operating button (66) of the main device (24) advances away from thecarriage (l8).

6. A flying cutting tool machine according to claim 5 wherein theabutment on the carriage (I8) is in the form of a bush (72) whichreceives a part of the operating button (66) and the abutment (70) isprovided by a flange.

7. A flying cutting tool machine according to claim 2 wherein is theimprovement that the cutting tool (34) is arranged to be fed upwardly toeffect a cutting operation on the stock and an upper clamp (52, 54) ismovable downwardly by a clamping fluid pressure piston and cylinderdevice (56) and is mounted on a pillar structure (60) of the carriage(18) to effect a coarse adjustment of the upper clamp to accommodate barstock (20) of different cross-sectional sizes.

8. A flying cutting tool machine according to claim 7 wherein is theimprovement that the pillar structure comprises I two spaced apartpillars (60) which are supported in bushes 65' (59) on the carriage andare vertically adjustable therein and support a crossbar (58) carryingthe upper clamp (52, 54).

9. A flying cutting tool machine according to claim 8 wherein is theimprovement that the pillar structure (60) comprises a further crossbar(62) which forms a positive stop for a cutting tool mounting means (32)during the feed movement of said cutting tool mounting means.

10. A flying cutting tool machine according to claim 9 wherein is theimprovement that the pillar structure (60) carries a switch (94 which isin consequence adjustable with said structure (60) and is arranged tocause reversal of the feed movement of the cutting tool (34).

1. A flying cutting tool machine for cutting substantially horizontallyadvancing bar stock (20) and having a carriage (18) with clamping means(44, 52, 46, 54) by which the carriage is clamped to the bar stock at astarting position and also having a cutting tool (34) movable to cutthrough the advancing bar stock and be withdrawn therefrom whereupon theclamping means release the carriage from the bar stock to enable a mainfluid pressure operated piston and cylinder device, which is notattached rigidly to the carriage and does not influence the advancemovement of the carriage, to return the carriage to the startingposition wherein is the improvement that a control means (90, 77, 93) isassociated with the carriage (18) and with a movable member (64) of themain fluid pressure device (24) to cause said movable member (64) of themain fluid pressure device (24) to be advanced by fluid pressure thereinsubstantially in unison with the carriage (18) whilst the clamps securethe said carriage to the stock so as to be advanced solely by the stockuntil the cutting tool (34) has finished a cutting operation and isclear of the bar stock (20) and then to cause said movable member (64)of the said main fluid pressure device (24) substantially simultaneouslyto return the carriage (18) to the starting position.
 2. A flyingcutting tool machine for cutting substantially horizontally advancingbar stock (20) and having a carriage (18) with clamping means (44, 52,46, 54) by which the carriage is clamped to the bar stock at a startingposition and also having a cutting tool (34) movable to cut through theadvancing bar stock and be withdrawn therefrom whereupon the clampingmeans release the carriage from the bar stock to enable a main fluidpressure operated piston and cylinder device, which is not attachedrigidly to the carriage and does not influence the advance movement ofthe carriage, to return the carriage to the starting position wherein isthe improvement that a control means comprises a multiway fluid pressurevalve (90) and a followup fluid pressure release valve (77), saidmultiway valve being connected to a fluid pressure supply source (92)and to opposite ends of the main fluid pressure piston and cylinderdevice (24) which is double-acting and said multiway valve being alsoconnected to the followup valve (77) which is supported by and movablewith the carriage (18) and which followup valve (77) is operablyassociated with the movable member (64) of said main device (24) wherebyduring advance of the carriage (18) by the bar stock from the startingposition the followup valve (77) catches said movable member (64) of themain device (24) to open said followup valve (77) and open one side ofthe said main device (24) to exhaust to permit a greater fluid pressureon the other side of said main device (24) to advance said movablemember (64) of said device away from the followup valve (77) which willthen close to stop further advance of the said movable member (64) ofsaid main device (24) until the carriage (18) and the followup valve(77) again catch the said movable member (64) of said main device torepeat the cycle until the tool (34) has finished the cutting operationand is clear of the stock (20) from which the carriage (18) is thenreleased whereupon the multiway valve (90) connects said one side of themain device to the fluid pressure supply (92) and the other side of saidmain device to exhaust to reverse the operation of the said main device(24) and return the carriage (18) to the starting position.
 3. A flyingcutting tool machine according to claim 2 wherein is the improvementthat said other side of the said main device (24) is connected toexhaust through a pressure relief valve (93).
 4. A flying cutting toolmachine according to claim 2 wherein is the improvement that thefollowup fluid pressure release valve (77) comprises a port (82)connected to the multiway valve (90), an actuating lever (76), a spring(80) to urge the lever towards the port to close said valve, said levercooperating with an operating button (66) of said movable member (64) ofthe main device (24) whereby the lever is urged away from the port toopen said valve.
 5. A flying cutting tool machine according to claim 4wherein is the improvement that the carriage (18) is provided with anabutment (72) and the operating button (66) is provided with an abutment(70) and said abutments cooperate to enable the main device (24) toreturn the carriage (18) to the starting position and said abutmentsseparate when the operating button (66) of the main device (24) advancesaway from the carriage (18).
 6. A flying cutting tool machine accordingto claim 5 wherein the abutment on the carriage (18) is in the form of abush (72) which receives a part of the operating button (66) and theabutment (70) is provided by a flange.
 7. A flying cutting tool machineaccording to claim 2 wherein is the improvement that the cutting tool(34) is arranged to be fed upwardly to effect a cutting operation on thestock and an upper clamp (52, 54) is movable downwardly by a clampingfluid pressure piston and cylinder device (56) and is mounted on apillar structure (60) of the carriage (18) to effect a coarse adjustmentof the upper clamp to accommodate bar stock (20) of differentcross-sectional sizes.
 8. A flying cutting tool machine according toclaim 7 wherein is the improvement that the pillar structure comprisestwo spaced apart pillars (60) which are supported in bushes (59) on thecarriage and are vertically adjustable therein and support a crossbar(58) carrying the upper clamp (52, 54).
 9. A flying cutting tool machineaccording to claim 8 wherein is the improvement that the pillarstructure (60) comprises a further crossbar (62) which forms a positivestop for a cutting tool mounting means (32) during the feed movement ofsaid cutting tool mounting means.
 10. A flying cutting tool machineaccording to claim 9 wherein is the improvement that the pillarstructure (60) carries a switch (94) which is in consequence adjustablewith said structure (60) and is arranged to cause reversal of the feedmovement of the cutting tool (34).